Influenza is common in school-aged children, has high attack rates, and is a leading cause of school absenteeism. It is associated with substantial morbidity, mortality and economic costs. Recently, we have shown significant relationships between school calendars and prevalence of medically-attended visits for all-cause respiratory infections in school-aged children and children 0-4 years. Despite reasonable efficacy of influenza vaccines at these ages, however, only one third of school-aged children are immunized. Because influenza is efficiently spread within school settings, rates of school absenteeism have been used in influenza surveillance programs and proposed as a component of early warning systems. The lack of specificity, however, presents significant limits. Since the advent of modern molecular detection methods, there have been no studies coupling absenteeism with direct identification of pathogens to assess the value of cause-specific absenteeism for early detection of influenza. Program Goal: The goal of ORCHARDS is to determine rapidly the causes of school absenteeism across a school district over a three-year period and to assess the comparability between surveillance based on influenza-specific absenteeism and a multiple layers of complimentary influenza surveillance centered on this school district. Methods: We will actively recruit up to 500 children on the first day of their schol absence due to respiratory infection from the Oregon School District, Dane County, Wisconsin, in each of three years. We will use the Jackson criteria to confirm ARI, and collect nasal and NP/OP specimens at the student's home for virological testing. Detailed demographic, epidemiologic and symptom data will be collected at that visit. Nasal specimens will be tested within 2 hours using a SOFIA RIDT platform with instantaneous wireless transmission of results to a secure server. NP/OP specimens will be transported to the Wisconsin State Laboratory of Hygiene for near real-time molecular testing for the presence of 17 respiratory viruses using rT-PCR on a Qiagen Multiplex PCR platform. The temporal patterns of cause-specific absenteeism will be compared to influenza surveillance based on (1) cause-specific medically attended visits to four surrounding clinics, (2) EHR surveillance for ILI in two layers of surrounding primary care clinics, (3) ILI-Net for Wisconsin, (4) virological surveillance based on a network of Wisconsin PCR and RIDT sites. Significance: School-based influenza surveillance provides an opportunity for extremely early detection of influenza in a community. Coupling cause-specific absenteeism with high sensitivity, wireless RIDT with PCR confirmation allows for inexpensive, rapid identification of seasonal and pandemic influenza.